This article is the first in a series The Conversation Africa is running on invasive species.

Let’s say you’re travelling from Uganda to South Africa for business. You finally arrive at your hotel after a long day and decide to change before dinner. You unlock and unzip your luggage, but there’s something in your bag that you didn’t pack. As you reach for a clean shirt, a moth flies out. Did that come with you all the way from Uganda? It’ll be fine, right? Surely, something so small won’t cause any harm.

Species are intentionally or accidentally transported by humans between continents to regions where they are not native. With the help of humans or by natural means like flight, these alien species can also spread within continents.

Their spread within continents can be rapid, affecting both the ecology as well as societies and the economy. Unfortunately, it’s really challenging to prevent species from spreading. Given the vast amount of people and goods that are transported between and around continents they can easily be moved across oceans as well as between countries.

The spread of alien species

Many alien plants and animals have been introduced to Africa from other regions and then have spread from country to country, often having devastating effects.

Take the larger grain borer beetle, (Prostephanus truncatus) which is thought to have arrived on the continent in imported grain from Mexico and central America. The beetle was introduced to Tanzania before 1984, Togo before 1981 and Guinea before 1987. It then spread across the continent and within 20 years could be found further south in South Africa.

The beetle attacks crops such as maize and cassava, threatening food security and the livelihoods of the poor. Infestations often destroy maize that’s been stored by farmers, forcing them to buy maize as well as lose income they could have earned from selling any excess.

But alien species don’t just arrive from abroad. Many that are native to parts of Africa have also spread to countries on the continent where they are not native.

An example is the fish commonly known as the Mozambique tilapia (Oreochromis mossambicus) which is native to rivers on the east coast of southern Africa. Fishermen have transported the Mozambique tilapia to other areas and it is now found in river systems in southern and western South Africa and Namibia.

The Mozambique tilapia is a popular species for fishing but it can pose a threat to native fish and has been responsible for the disappearance of native species in some regions.

The spread of alien species within Africa is by no means a new thing. For instance, the bur clover (Medicago polymorpha), a plant from northern Africa, might have been accidentally transported by humans to South Africa as early as 760 AD.

A high and increasing threat

Recently a number of alien species have spread extremely rapidly across the continent, posing a particularly high threat to food security and livelihoods.

The fall armyworm, native to the Americas, was first recorded in west and central Africa in early 2016 and then in South Africa in January 2017.Shutterstock

One is a caterpillar known as the fall armyworm (Spodoptera frugiperda). The species, native to the Americas, was first recorded in west and central Africa in early 2016 and then in South Africa in January 2017.

The moths of the armyworm are strong fliers and the species may have spread through flight to South Africa from other African countries. Although the species attacks a wide range of crops, it poses a particularly serious threat to grain farmers. It is extremely difficult to manage.

Another example is a wasp known as the bluegum chalcid (Leptocybe invasa), which is native to Australia. In 2000 it was detected in Israel and shortly afterwards it was reported in Uganda and Kenya. From there it spread rapidly to many African countries including Zimbabwe, Mozambique, and Tanzania and was finally detected in South Africa in 2007. The insect probably reached Israel on live plant material and spread into Africa the same way, or was carried by people travelling between countries.

The wasp causes swelling or growths on eucalyptus trees, which can lead to decreased growth and tree death. As eucalyptus trees are an important source of income and fuel, this species could have an impact on the livelihoods of locals in these countries.

Preventing the introduction and spread

Once a species is introduced to one African country it’s highly likely it will spread to others on the continent because borders checks are weak.

The introduction and spread of species could be reduced if countries introduced biosecurity systems. These are used extensively in countries like Australia and New Zealand and involve using technology to check for alien species when people and goods enter a country. In Australia this involves inspecting goods, vehicles and luggage before they enter the country.

But even these systems aren’t a guarantee that species won’t spread. African countries would need to work together and share information and skills. This would also allow countries to prepare for the arrival of species, and to draw up plans to reduce their impact.

This is a tall order. But as a country’s defence against alien species introductions is only as strong as that of its neighbours, such action would benefit all of the countries involved.

Australia’s greenhouse gas emissions are on the rise. Electricity emissions, which make up about a third of the total, rose 2.7% in the year to March 2016.

Australia’s emissions reached their peak in 2008-2009. Since then total emissions have barely changed, but the proportion of emissions from electricity fell, largely due to falling demand and less electricity produced by coal. But over the last year demand grew by 2.5%, nearly all of this supplied by coal.

Why did demand fall?

To understand this trend we need to look at data from Australia’s National Electricity Market (NEM), which accounts for just under 90% of total Australian electricity generation. While the NEM doesn’t include Western Australia or the Northern Territory, it has much better publicly available data.

The chart below shows electricity generation from June 2009 to March 2016.

Hugh Saddler, Author provided

The most important things to note are that, until February 2015, overall generation fell and the amount of electricity supplied by coal also fell. These two trends are closely related.

In June 2009, coal was supplying 84% of electricity, while 7% came from renewables (mainly hydro and wind) and 9% from gas.

Because renewables have near-zero short-run marginal costs (because they don’t have to pay for fuel) they will nearly always be able to outcompete coal and gas. This will be particularly so when demand for electricity falls.

Since June 2009 coal has been squeezed out by falling demand and a growing supply of renewables and gas. Until February 2015, total demand fell 8%, gas supply rose 43%, renewable supply grew 55% and coal supply fell 18%.

A dangerous trend

Since February 2015, however, these trends have reversed, which is very bad news for Australia’s emissions. Demand grew 2.5% and, combined with falling electricity supply from gas and renewables, coal picked up the slack, driving emissions 2.7% higher.

Why is demand increasing?

To understand why demand is increasing we can look at the three major consumer groups – industry, business and households – as you can see in the figure below.

Victoria is excluded because differences in the timing of industry reporting to the AER mean that the most recent data are not available. Exclusion of Victoria does not change the overall picture, as it has shown the same trends as the other NEM regions.Hugh Saddler using data from AER and AEMO, Author provided

After growing until 2012, industry demand fell sharply because of closures of several major establishments, most notably aluminium smelters in New South Wales and Victoria.

Since 2015 very rapid growth has occurred in Queensland, driven by the coal seam gas industry. Extraction of coal seam gas requires the use of enormous numbers of pumps, compressors and related equipment, to first extract the gas from underground and then to compress it for pipeline transport to the LNG plants at Gladstone.

Initially, the industry used gas engines to power this equipment, but then realised that electric motor drive would cost less. The government-owned Queensland electricity transmission business, Powerlink Queensland, is making major investments (paid for by the gas producers) in new transmission lines and substations to meet this new demand.

As a side note, the LNG plants in Queensland will not themselves use electricity from the grid, but will use about 120 petajoules of gas each by 2017-18, adding another 6 million tonnes to national greenhouse gas emissions.

Now electricity prices have stabilised or are falling and attract much less attention. Moreover, fewer appliance energy standards are being introduced, slowing the decrease in demand.

The result is that average electricity consumption per household, which fell by 17% between 2010 and 2014, has stabilised. In the absence of stronger energy efficiency policies and programs, residential electricity consumption can be expected to grow in line with population.

Business is the largest of the three consumer groups. Electricity demand fell slightly between 2010 and 2014. This is because electricity intensity, the amount of electricity needed to produce economic value, fell 3% each year; that is, slightly faster than the economy grew.

It now appears, however, that in the past year the fall in electricity intensity has almost ceased, so that total consumption has increased in line with economic growth.

Energy productivity is the economic value produced per unit of energy. The 40% goal is equivalent to a reduction of just under 30% in the energy intensity of the economy.

In the case of electricity, had the trend of the period 2010 to 2014 continued, this would have been achieved quite easily. It now appears to be a much more challenging goal, requiring the urgent introduction of a range of new energy efficiency policies and programs.

CORRECTION: The lead image has been corrected. It previously incorrectly showed aluminium works at Gladstone, Queensland.

We explored this apparent paradox with the help of a simple model that simulates the current relative proportions globally of the area of remaining tropical forest, and the area that has been cleared for agricultural development. We used the model to look at what happens to these proportions when networks of conservation reserves expand.

Our research led to two insights: both the area of forest protection and the area of clearing for development can expand at the same time; and the governance regimes responsible for protected areas can actually be weakened by protected area expansion. This is because pressure for the creation of new protected areas comes largely from public discourse.

Forests and forces

In our model we depicted tropical forestlands as consisting of protected forests; traditionally managed or “unallocated” forests; and cleared agricultural land – plausible categories that broadly reflect the current status and areas.

We then modelled the different governance regimes (and feedbacks such as public discourse) responsible for this current status, regimes that:

a) protect unallocated forest;

b) develop (and clear) unallocated forest for agriculture;

c) maintain current habitat and restore agricultural land to forest, thereby opposing clearing for development.

We use the model to present three plausible scenarios of governance regime and land-use change trajectories.

The forces that affect land use in forested areas.

Our dynamic hypothesis depicted in the figure shows how the driving forces of development and protection, while competing for the remaining stock of forest habitat, do not necessarily oppose each other. Consequently the total stock of forest habitat can decrease while the area of protected forest increases.

The force that directly opposes clearance of forests for development is the one that maintains existing unprotected forest use regimes or that seeks to restore cleared forest.

The relative power of the governance regimes that “develop”, “protect”, or “maintain/restore” will determine what ultimately happens to the area of remaining forest habitat. Biodiversity loss will only stop when the net loss of forest habitat each year is zero – which means halting the clearing of tropical forest for agricultural development, as well as increasing protected areas.

But in the real world we are doing the opposite – investing heavily in the force that drives tropical forest clearing. The leaders of the G20 nations recently gave a huge boost to the power of development regimes, by pledging to invest up to US$70 trillion on new infrastructure projects by the year 2030. This is precisely the kind of driving force that will harm wildlife conservation, and which the growth of protected areas will fail to counter.

It seems counter-intuitive, but our research suggests that increasing the area of the world’s conservation reserves can also reduce the perception of the risk of ongoing biodiversity loss, primarily because the focus on the 17% protection targets takes our eye off the critical issue of halting habitat loss. As a result, the global distribution of protected areas is currently “high and far”, skewed toward mountainous areas and places far from development frontiers. If achieving 17% leads the public to conclude that biodiversity is now safe, it can lower the main feedback currently giving power to the protect force – public pressure for political action.

This is compounded by the phenomenon of extinction debt – the time delay between habitat loss and the resulting extinction of species that live here – which hides the impact of development on wildlife in both protected and unprotected areas.

What do we do about it?

Conservation has traditionally sought to identify and protect “representative samples” of different types of ecosystems. Recently, however, there has been an increased interest in identifying and protecting areas based on cost-effectiveness criteria.

We suggest instead that one useful leverage point for slowing tropical biodiversity decline would be to concentrate on placing protected areas near active agricultural frontiers, which could help to constrain the march of agriculture through tropical forests.

This approach has already been shown to work in urban planning, including in Australia, where it has been used to fight urban sprawl. A second useful leverage point is to set global targets that include both a percentage for protection and an overall percentage for remaining forest habitat. Globally, forest cover now is at 62% of its original extent, while 75% has recently been identified as the extent necessary to stay within planetary boundaries.

Sharing is caring

There is currently much debate in the conservation literature about “land sparing or land sharing”. Our scenarios suggests that while land sparing through rapid protected area expansion has immediate conservation benefits, these benefits are lost over time as species populations eventually crash. The land-sharing scenario, through strengthening the power to maintain current forest habitats, suggests better biodiversity outcomes in the long term.

Our analysis suggests that human activity will continue to damage wildlife diversity, in spite of successful efforts to meet the target of protecting 17% of Earth’s land surface. The reason is that a large percentage of natural habitats are disappearing in the face of development, particularly through the clearing of tropical forests for agriculture.

This destruction will continue because the overall balance of land management is still geared towards ongoing clearing for development rather than sustainable re-development of our current human footprint. Getting out of this trap will require an understanding of the processes that reinforce this perverse situation, and the realisation that this system needs to be redesigned.

This is a new frontier in conservation science, and our new analysis is hopefully a first step towards unravelling this complex social-ecological problem.

What we need to do next is to identify the critical feedback relationships that can empower natural resource management, and to put reasonable limits on the power of development regimes. Otherwise, the world’s biodiversity will continue to dwindle even if conservation reserves expand rapidly.

This article was coauthored by Craig Miller, a former researcher with CSIRO Sustainable Ecosystems.